Escape of particles from pulsar bow shock nebulae
Abstract
An increasing number of evolved pulsar wind nebulae have been observed in the last years to show extended X-ray features, apparently developing close to the pulsar location and defying expectations from canonical MHD models, being strongly misaligned respect to the pulsar direction of motion, asymmetric and collimated up to long distances from the parent nebula. Extremely extended TeV halos have also been observed surrounding old pulsar wind nebulae, requiring the presence of high energy particles diffused around the source. Moreover pulsar wind nebulae are candidate to be primary sources, in contrast to dark matter models, of the positron excess revealed by different instruments in the cosmic ray spectrum and are then expected to replenish the ISM with electrons and positrons.
It was suggested that particles can efficiently escape from those systems, with some degree of charge separation, and produce the observed signatures. With the present project we have investigated this possibility and show that, not only particles are able to efficiently stream out from evolved pulsar wind nebulae, but that the outflow can easily be asymmetric and charge separated, accounting for the observed features.- Publication:
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Memorie della Societa Astronomica Italiana
- Pub Date:
- 2020
- Bibcode:
- 2020MmSAI..91..321O
- Keywords:
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- ISM: supernova remnants;
- ISM: cosmic rays;
- magnetic fields;
- MHD;
- methods: numerical;
- pulsars: general